Second-order four-stroke apparent motion

Mather, George and Murdoch, Linda (1996) Second-order four-stroke apparent motion. In: Association for Research in Vision and Ophthalmology annual meeting, April 21-26 1996, Fort Lauderdale, Florida.

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Item Type:Conference or Workshop contribution (Paper)
Item Status:Live Archive


Purpose: Four-stroke apparent motion displays contain luminance edges that alternate in position and synchronously reverse in contrast polarity. As a result they appear to move unidirectionally, a percept that is readily accommodated by current models of motion energy analysis. Second-order motion displays contain texture-defined edges, and there is some evidence that they excite second-order energy detectors that are fed by 'texture-grabbing' transforms. However, different second-order textures require different transforms, and it is not clear how many transforms are available to second-order energy analysis. We used the effectiveness of second-order four-stroke apparent motion as a diagnostic test for the availability of various tranforms to motion energy analysis. Methods: Seven four-stroke displays were created, containing contours defined by modulation of - luminance; contrast; flicker; disparity; size; motion parallax; and orientation. In each case we measured the effectiveness of both the whole cycle, and of fractions of a cycle, at generating unidirectional apparent motion. Results: All except three of the displays proved effective in both part- and whole- cycle presentations. The three failures involved flicker modulation, disparity modulation, and motion parallax. Conclusions: The successful displays contained contours that can be revealed by transformations incorporating spatial filtering and rectification; the unsuccessful displays all require more complex transformations (spatiotemporal filtering or binocular analysis). The former transformations thus appear to feed into second-order energy analysis, but the latter transformations do not.

Additional Information:Investigative Ophthalmology and Visual Science vol 37 no 3
Keywords:secondorder motion; four-stroke motion
Subjects:B Subjects allied to Medicine > B140 Neuroscience
C Biological Sciences > C830 Experimental Psychology
Divisions:College of Social Science > School of Psychology
ID Code:16126
Deposited On:04 Dec 2014 13:51

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